Condenser-operating mechanism for variable condensers



June 1 ,1927. 1,631,788

M. H. BENNETT CONDENSER OPERATING MECHANISM FOR VARIABLE CONDENSERS Filed May 28, 1926 2 Sheets-Sheet l avwewfoz m V QL June 7,1927. ,631,788

M- H' BENNETT CONDENSER OPERATING MECHANISM FOR VARIABLE CONDENSERS Filed May 28, 1926 2 Sheets-Sheet 2 .2 V I K m 3 3 Patented June 7, 1927..

UNITED STATES 1,631,788 PATENT OFFICE.

MORRIS HpBENIlIETT, OF WATERBURY, CONNECTICUT, ASSIGNOR TO SCOVILL MANU- FACTURING COMPANY, OF WATERBURY, CONNECTICUT, A CORPORATION OF CON- CONDENSER-OPERATING MECHANISM FOR VARIABLE CONDENSERS.

Application filed May 28,

This invention relates to condenser operating mechanism for variable condensers.

One object of the invention is to provide a slow motion drive or so-called Vernier drive for a variable condenser, such as a condenser used in radio apparatus, the invention being particularly applicable to a rotary variable condenser and having the advantage that both the quick motion drive and the slow motion drive are operated by the same knob.

A further objecgt of the invention is to provide an operating mechanism suitable for operating a plurality of variable condensers from one knob, while at the same time permitting the individual condensers to be separately adjusted to a limited extent.

The inventionwill first be described in connection with the accompanying drawings showing one specific embodiment of the invention, and then will be more particularly pointed out.

In the drawings,

Figure 1 is a plan view illustrating the invention applied to three rotary variable condensers, such as are employed in radio receiving isets;

Figure 2 is a front view of the same;

Figure 3 is an enlarged detail front view and Figure 4 a horizontal section, partly in elevation, of an individual driving means for the end condensers in Figure 1; and

Figure 5' is an enlarged sectional view \illustrating the individual driving means for the middle condenser in Figure 1.

These drawings illustrate a. tuning apparatus for a radio receiver, in which there are three variable condensers of any desired construct-ion, these condensers being indicated generally at A, B and C, as of the usual type having a set of rotatable plates. Each condenser has a rotor shaft, which when rotated to the desired extent will. change the capacity of the condenser, and thereby vary the period of any circuit in which said condenser is included.

On each rotor shaft, a, b and c, respectively, there is mounted a pulley or band wheel. The pulley for the intermediate condenser B has its face wide enough to receive'two belts and is fixed to its rotor shaft. In the present embodiment of the in: vention, this pulley comprises a drum D and a hub D. The drum D may advantageously be made of stamped or pressed sheet metal and has its end disk provided with a central opening which fits over a reduced portion of the hub D. A slow motion disk I also fits over this reduced ortion of the hub, the end of the latter being swaged or riveted over the said driving disk I, so that it,and the drum D are both securely fastened to the hub D, as will be clear from Figure 5. The hub D is secured to the rotor shaft 5 in any suitable way, as for example by a set-screw, indicated at 10, Figure 5. The slow motion disk I runs between two friction disks 11 and 12, which are mounted on a slow motion or Vernier shaft 13, these disks being spaced apart by a spacing washer 14. The friction disks 11 and 12 are made of compressible resilient material such, for example, as soft rubber. The slow motion shaft 13 is formed to have three different diameters, as will be clear from Figure '5, the intermediate diameter having a screw-threaded portion, as shown.

At each side of the pair of friction-disks 11 and 12 there are placed washers 15 and 16 respectively. One the front end of the slow-motion shaft 13 a front sleeve 17 is provided. This has an internal screw-thread which engages the thread on the intermediate portion of the shaft 13. The front end of the sleeve 17 projects through the front plate X of the receiver cabinet, and ,is provided with a knob K, said knob carrying a i set screw 18 which passes through a hole in the front sleeve 17 and engages the slowmotion shaft 13, thereby holding the knob, the sleeve 17 and the shaft 13 together.

The rear end of the slow-motion shaft 13 is located within a rear sleeve or bushing 19 whose rear end is reduced in diameter,

passed through an: opening in the condenserframe front plate, Y, and then flanged overthe plate Y but in such a manner that while the bushing 19 is held to the said plate Y it is rotatable in the opening. The slow motion shaft 13 base slotted head 20 at its rear end, and has a slot in its front end, as will be clear from Figure 5. A spiral spring 21 surrounds the rear sleeve or bushing 19, this spring being under compression between the front plate Y and the washer 15, and thereby tendin to force the said washer against, the rear 'riction disk 11 and maintain a substantially uniform pressure of the latter against the rear side of the slow motion driving disk I. It will be noted that by the construction described the front friction disk 12 may be adjusted by screwing or unscrewing the front sleeve 17, so that said friction disk 12 will properly contact with the front side of the slow motion driving disk I. The disk I is made of resilient material such as sheet metal. The knob K serves to rotate the shaft 13 and sleeves 17 and 19, as a unit, in the condenser frame front plate Y.

The pulleys for the condensers A and C are alike. Each comprises a drum E, F, respectively, and a hub E, F, respectively.

The drums E and F are not in alignment with each other, but each is arranged to be connected by its own belt with the double width drum D, these belts being indicated at G, H, respectively.

Since the driving mechanisms for the condensers A and C are alike, onlyone will be described, reference being made to the mechanism for condenser A which is illustrated in Figures 3 and 4.

The drum E is secured to its hub E by providing the hub with a reduced portion which enters a central hole in the drum E, the end of the reduced portion of the hub being flanged over the drum to hold the latter securely. The pulley thus formed is not fixed to the rotor shaft a. To the drum E is pivoted a double yoke device L Which has two airs of arms, the arms of one pair being indicated at 22 and 23, Figure 3, and those of the other pair being indicated at 24, 25. The device L is pivoted on a pin 26 which passes through a spacer block 27 and drum E and is riveted at both ends as shown in Figure 4, the pin 26 having an enlarged portion near its outer end in order to hold the spacer block 27 tightly to the drum. I The arms 24: and 25 are arranged to engage a wrist pin 28 secured to a disk 29 adjustably fixed to the rotor shaft a by a set screw 30.

On the front end of the rotor shaft is mounted a sleeve 31 provided at its rear end with an eccentric 32 arranged to lie between and contact with the arms 22 and 23 of the yoke device L. The sleeve 31 is held to the rotor shaft by a machine screw 34 and car ries a detent-pin 33, for a purpose hereinafter described. The sleeve 31 projects forward of the front plate X of the cabinet and is reduced in diameter. On this projecting portion, a knob M is secured by means of a screw 35. k v

For the purpose of maintaining a slight amount of friction on the drum-E, there is provided a friction device comprising a spring arm 36 having a foot at its rear end,

. which is .suitably secured to the condenser frame front plate, as for example by means of one of the screws which hold the front bearing plate of the condenser. The front end of the spring arm 36 is provided with jaws which receive and hold a felt block 37 which rubs lightly against the inner face of the drum E. The friction device is essential when a condenser, such as A or C is to be used alone, that is to say, when it is not belted to another condenser, and is sometimes of advantage where such a condenser is belted to others, as it prevents any overrunning of the condenser when driven from another condenser shaft.

The operation of the condenser driving mechanism shown in Figures 3 and 4 will first be described, assuming that it is not connected up, as by a belt, for operation with another condenser.

When the knob M is turned in a clockwise direction, as viewed by the operator, (see Figure 3), the first effect is to rotate the sleeve 31 and with it the eccentric 32. When the latter rotates clockwise, it swings the yoke device L so that the arm 22 swings nearer to the center of the rotor shaft and the arm 23 swings farther away. .At the same time the arms 24; and 25 swing in the same direction as arms 22 and 23 and, by.

acting on the wrist-pin 28, rotate the disk 29 in a clockwise direction. As this disk is fixed to the rotor shaft a, the latter is rotated clockwise. When the eccentric 29 has been rotated clockwise approximately ninety de grees from the position shown in Figure 3 by the turning of the knob M, the pin 33 comes into contact with the end of the arm 22, and thereafter any further rotation clockwise of the knob M and eccentric 29 will carry the rotor shaft around with the knob, the parts then acting as if the knob were locked to the rotor shaft a. Therefore, after the first rotation of the knob M to the extent of approximately ninety degrees from the position shown in Figure 3, the knob serves to turn the rotor shaft and its plates as a quick motion driving device. If new the knob M is turned backward, that is, counterclockwise, the first effect is to turn the eccentric 29 counterclockwise, its pin 33 leaving the end of arm 22 and moving around in a circular orbit until it contacts with the end of arm 23, this movement amounting to about one hundred and eighty degrees. During this time the eccentric 29 swings the yoke-device L so that the arm 23 swings nearer to the center of the rotor shaft and the arm 22 swings farther away from said center. The angular movement of the arms .22 and 23 is much less than the angle of rotation of the knob M and the eccentric 29, the amount depending upon the throw of the eccentric 29, and the distance from the pivotal axis of the yoke device to the axis of the eccentric 29. Hence for about 180 degrees initial rotation, the knob Ill I M acts as the knob-of a slow motion driving device 'to swingthe yoke device through a much smaller angle than that through which the knob turns.

As the yoke device is swung,- the arms 24:

and 25. swing through the same angle as the arms 22 and 23 and move-the wrist pin 28 through an'orbi't concentric with the axis of "the rotor shaft, thus rotating the disk 29 and with it the rotor shaft and the rotor plates through an angle which is determined substantially by the distance from the pivotal axis of the yoke device to the wrist pin, as compared with the radius of the orbit of the wrist pin: Bymaking the arms 24 and 25 relatively short and the radius of the orbit of the wrist pin relatively large, the are through which the rotor shaft is rotated may be very small as compared with the angular movement of the knob M. In the usual operationjof tuning a radio circuit, where a driving device of this type is used on a con.-

denser not coupled to any other condenser, the knob M may be turned quickly and to. a sufficient extent to and: slightly past the point or proper tuning and then the knob may be turned backward slowly to give the rotor shaft a slow motion drive in the reverse direction until the point of proper tuning is reached. The purpose of the friction device 36, 3'1 is to prevent the drum E turning merely by the friction between its hnb condenser A or that of condenser G may be E and the rotor shaft 12. i Where a plurality of condensers are coupled, as for example by a belt or belts, the movement-of one condenser mob will moveall the condensers so connected, thus allowing several circuits to be tuned simultaneously by the operation of one knob. At the same time the slow motion or vernier drive such as is used for condensers A or C allows such condensers to be given a slight oorrectional movement without moving the con denser coupled to it;

Where a slow motion or Vernier drive of the type shown in Figure 5 is employed, the

operation of the slow motion knob will drive not only its own'condenser, but also will rotate the pulleys of the other condensers connected to its pulley, whereby the said other condensers may be adjusted simulta neously.

The particular arrangement of driving mechanism for coupling three condensers has been found to be very suitable for radio receiving apparatus, because the knob of used as a quick motion drive for all the condensers, and then the knob K of condenser B -may be rotatedin both directions as a slow motion or-vernier drive for all the condensers. Finally the knobs of condensers A or C or both may be individually operated in a backward direction as a slow motion drive for its own condensers, to correct for of the type disclosed in application of Bennett and Colina, Serial No. 55,656, filed September 11, 1925 and the slow motion drive for the condenser B is of the general type disclosed in my application, Serial No. 97,529, filed March 26, 1926,

What ll claim is:

1. A driving device for circuit tuning elements, said driving device comprising a rotatable shaft for varying the tuning element, a wrist pin carried by the shaft, an eccentric, --means for rotating said eccentric about an axis coincident with the longitudinal axis of the shaft, a rotatable member loosely mounted on the shaft, a double yoke device pivoted on said rotatable member and provided with two pairs of-arms, one pair receiving the wrist pin between them and the other pair receiving the eccentric between them, and means carried by the eccentric for alternately engaging and driving either arm of the pair between which the eccentric is located to rotate the yoke, as an entirety, about the axis of the shaft.

2. A driving device .for circuit tuning elements, said driving device comprising a rotatable shaft for varying the tuning element, a wrist pin carried by the shaft, an

eccentric, means for rotating said eccentric about an axis coincident with the longitudinal axis of the shaft, a rotatable member loosely mount-ed on the shaft, a double yoke device pivoted .on said rotatable member and provided with two pairs of arms, one pair receiving the wrist pin between them and the other pair receiving the eccentric between them, means carried by the eccentric for altern'ately engaging and driving either arm of the pair betweenwhich the eccentric is located to rotate the yoke, as an entirety, about the axis of theshaft, and means tending to hold said loosely mounted rotatable member stationary when the engaging means carried by the eccentric is not in driving action against either of said arms.

3. A driving device for a pluralityof' circuit tuning elements, said driving device comprising a rotatable shaft for varying one of the tuning elements, a wrist pin carried by said shaft, an eccentric, means for rotating said eccentric about an axis coincident with the longitudinal axis of said shaft, a pulley loosely mounted on said shaft, a double yoke device pivoted on said pulley and provided with two pairs of arms, one pair receiving the wrist pin between them and the'other pair receiving the eccentric between them, means carried by the eccentric for alternately engaging and driving either arm of the pair between which the eccentric 1 is located to rotate the yoke, as an entirety, about the axis of the shaft, .21, second rotatable shaft for varying another tuning element, a pulley fixed thereon, and a belt connecting both pulleys. v

4. A driving devicefor a plurality of circuit tuning elements, said driving device comprising a rotatable shaft for varying one of the tuning elements, a wrist pin carried by said shaft, an eccentric, means forrotating said eccentric about an axis coincident with the longitudinal axis of said shaft, a pulley loosely mounted on said shaft, a

arm .of the pair betweenwhich the eccentric is located to rotate the yoke, as an entirety, about'the axis of the shaft, a second rotatable shaft for varying another tuning element, a pulley fixed thereon, a belt connecting both pulleys, and a slow motion drive for said second rotatable shaft.

In testimony whereof, I have hereunto set 30 my hand.

MORRIS H. BENNETT. 

